When the 1783 treaty with Great Britain ended the Revolutionary War, America was a land of 13 former colonies clustered along the Eastern Seaboard. While the chartered boundaries of some of these states extended to the Pacific Ocean, westward expansion essentially stopped at the Appalachian Mountains. During the 1800s, though, America experienced a growth spurt.

Louisiana Purchase

The purchase of more than 800,000 square miles from the Gulf of Mexico to the Canadian border was one of the best real estate deals in U.S. history, enthused Joseph Harriss in a 2003 issue of "Smithsonian Magazine." In 1801 President Thomas Jefferson initiated negotiations for its purchase. France’s leader, Napoleon, agreed to the sale in 1803 for $15 million. The territory almost doubled the size of the United States and provided access to lands beyond the Mississippi River.

Texas and Florida

Most of the southwestern United States and Florida belonged to Spain at the beginning of the 19th century. Spain surrendered the territory of Florida with the Transcontinental Treaty of 1819, and Florida became a state in 1845. Texas moved more quickly: It was annexed by the United States in March of 1845 and became a state by the end of December. Northern politicians objected to the annexation of such a large slave-holding state, while the South welcomed it.

Oregon Territory

By 1820 the territory of present-day Oregon, Washington, Idaho, and portions of Montana, Wyoming and British Columbia was shared by Britain and the U.S. In 1845 the U.S. began negotiations to divide the territory at 49 degrees north latitude, bisecting Vancouver Island. Americans considered that the United States had a "manifest destiny" to expand across the continent. Democratic presidential candidate James K. Polk promoted an even more expansionist stance with his campaign slogan "54 40 or Fight!" calling for a border at 54 degrees, 40 minutes north latitude. The 1846 Treaty of Washington set the border at the 49th parallel, but ceded all of Vancouver Island to Britain. The acquisition gave the U.S. valuable grazing and farm land, mineral reserves and coastal ports.

Half of Mexico

In the Mexican Cession, a result of the Mexican-American War, Mexico ceded more than 520,000 square miles to the United States. It was almost half of Mexico’s North American possessions and included modern-day California, Nevada and Utah, and parts of Arizona, Colorado and New Mexico. In the Gadsden Purchase of 1854, the U.S acquired more than 29,000 square miles that completed present-day New Mexico and Arizona.

Alaska

The United States purchased the 591,000-squale-mile Alaska Territory in 1867 from Russia for $7.2 million. The sale put an end to Russian trade and settlement expansion on the North American continent and began American’s rise as a trading power in the Pacific region. It also provided the U.S. with fishing, ports and mineral resources.

Hawaii, the Philippines and Puerto Rico

1898 was a banner year for American land acquisition with the annexation of the Hawaiian Islands and, at the end of the Spanish-American War, the purchase of the Philippine Islands and the annexation of Puerto Rico. The Philippine and Hawaiian acquisitions further advanced America’s influence in the Pacific, and the addition of Puerto Rico extended American influence into the Caribbean.